In recent years, digital cameras (image sensing devices) which can sense images and convert them into digital image data by simple operations have been prevalent. When an image sensed by such a camera is printed and used as a photo, it is a common practice to temporarily download the sensed digital image data from a digital camera to a PC (computer), execute an image process by the PC, and output the processed image data from the PC to a color printer, thus printing an image.
By contrast, for example, a color print system which allows a digital camera to directly transfer digital image data to a color printer without the intervention of any PC and can print it out, a so-called photo-direct (PD) printer which mounts a memory card that is used in a digital camera and stores sensed images and prints sensed images stored in the memory card has recently been developed.
Particularly, in order to directly transfer image data from a digital camera to a printer and print the image data, demands have arisen for standardization of interface specifications between a digital camera of each manufacturer and a printer, the operation method, and the like. One proposal for standardization is a guideline for realizing a DPS (Direct Print System).
However, in a case where a print process is interrupted by disconnecting a cable connecting a digital camera and a printer, or by turning off the printer, during printing of image data from a digital camera, details of restarting the print process by the printer are not defined. The present invention, therefore, proposes a method of realizing this.